"She is an incredible entity — it's unreal what that woman is," Tyler says. "She reminds me of the wonder around Madonna. Your average person thinks Madonna's singing 'Like a Virgin,' but if you look at what she endured in this man's-world music business of ripoffs, scoundrels and bastards, she's doing it like that. She's a phenomenon."

He then compared Swift to a beautiful guitar with beautiful strings.

"When they're strummed they sing these notes, but if you lean it up against the amp it starts feeding back," he comments. "If you lean Taylor up against her audience — and she's singing and they're screaming — it's a complete circuit. It's like a feedback loop."

Tyler reflects of his performance of "I Don't Want to Miss a Thing" with Swift as "being a real moment."

Swift's tour has had several surprise performances by country artists, including Dixie Chicks singer Natalie Maines for "Goodbye Earl" and Sam Hunt, who performed "Take Your Time" with her. The Band Perry joined her and performed "If I Die Young," while Dierks Bentley came onstage in Kansas City to sing "Every Mile a Memory." Earlier this month, Keith Urban sang two songs, "Somebody Like You" and "John Cougar, John Deere, John 3:16," in Toronto with Swift.